Time-domain diversity combining of signals for broadcast receivers

Abstract

Systems and methods are disclosed for time-domain diversity combining of radio frequency (RF) broadcast signals. Two channelized quadrature (I/Q) signals are generated by different tuner circuitry coupled to two different antennas, are converted to frequency-domain signals, and are used to generate frequency-domain diversity weighting signals. The frequency-domain diversity weighting signals are then converted to time-domain weights and applied to the channelized I/Q signals. The weighted and channelized I/Q signals are then combined in the time-domain to provide a time-domain diversity combined signal. The resulting combined signal can be further processed, as desired, such as by using a demodulator to generate demodulated output signals. Disclosed methods and systems can be applied to a variety of receiver systems configured to receive RF broadcast signals.

What is claimed is: 
     
       1. A diversity receiver system, comprising:
 first tuner circuitry configured to receive a radio frequency (RF) signal from a first antenna and to down-convert, digitize, and channelize the RF signal to generate a first time-domain channelized quadrature (I/Q) signal; 
 second tuner circuitry configured to receive a radio frequency (RF) signal from a second antenna and to down-convert, digitize, and channelize the RF signal to generate a second time-domain channelized quadrature (I/Q) signal; and 
 time-domain diversity combining circuitry configured to receive the first and second channelized I/Q signals, to convert the first and second channelized I/Q signals to frequency-domain signals, to analyze the frequency-domain signals to determine frequency-domain diversity weights for the first and second channelized I/O signals, to convert the frequency-domain diversity weights into at least one set of time-domain diversity weights, and to apply the time-domain diversity weights to generate a combined time-domain diversity I/Q signal based upon the first and second time-domain channelized I/Q signals; 
 wherein the time-domain diversity combining circuitry comprises:
 first FFT (Fast Fourier Transform) circuitry coupled to receive the first time-domain channelized I/Q signal and to output a first frequency-domain signal having multiple frequency components; 
 second FFT circuitry coupled to receive the second time-domain channelized I/Q signal and to output a second frequency-domain signal having multiple frequency components; 
 weight processing circuitry configured to receive the first and second frequency-domain signals and to generate the frequency-domain diversity weights; and 
 IFFT (Inverse Fast Fourier Transform) circuitry coupled to receive the frequency-domain diversity weights and to generate the at least one set of time-domain diversity weights. 
 
 
     
     
       2. The diversity receiver system of  claim 1 , wherein the first and second tuner circuitry are configured to receive OFDM (orthogonal frequency division multiplex) audio broadcast signals. 
     
     
       3. The diversity receiver system of  claim 1 , wherein the first tuner circuitry is integrated within a first integrated circuit and wherein the second tuner circuitry is integrated within a second integrated circuit. 
     
     
       4. The diversity receiver system of  claim 3 , wherein the time-domain diversity combining circuitry is integrated within a third integrated circuit, and wherein the third integrated circuit is combined in a multi-chip module with at least one of the first integrated circuit or the second integrated circuit. 
     
     
       5. The diversity receiver system of claim,  3  wherein the time-domain diversity combining circuitry is integrated within the second integrated circuit. 
     
     
       6. The diversity receiver system of  claim 5 , further comprising a demodulator configured to receive the combined time-domain diversity I/Q signal and to output a demodulated audio signal. 
     
     
       7. The diversity receiver system of  claim 6 , wherein the demodulator is configured to demodulate at least one of HD-Radio (High Definition Radio) broadcast signals or DAB (Digital Audio Broadcast) broadcast signals. 
     
     
       8. The diversity receiver system of  claim 7 , further comprising an FM (Frequency Modulated) demodulator integrated within the second integrated circuit and configured to receive the combined time-domain diversity I/Q signal, to demodulate FM broadcast signals, and to generate an FM demodulated audio signal. 
     
     
       9. The diversity receiver system of  claim 8 , further comprising blend circuitry configured to receive the FM demodulated audio signal and the demodulated audio signal and to generate a blended audio signal. 
     
     
       10. The diversity receiver system of  claim 6 , further comprising audio processing circuitry configured to receive the demodulated audio signal and to generate audio output signals, the audio processing circuitry being integrated within the first integrated circuit. 
     
     
       11. The diversity receiver system of  claim 10 , wherein the audio processing circuitry is configured to provide HI-FI audio processing. 
     
     
       12. The diversity receiver system of  claim 10 , wherein the demodulator is integrated within one of the first integrated circuit or the second integrated circuit. 
     
     
       13. The diversity receiver system of  claim 12 , wherein the demodulator is configured to demodulate at least one of HD-Radio (High Definition Radio) broadcast signals or DAB (Digital Audio Broadcast) broadcast signals. 
     
     
       14. The diversity receiver system of  claim 1 , wherein the weight processing circuitry is configured to generate a first set and a second set of frequency-domain diversity weights, and wherein the IFFT circuitry comprises first IFFT circuitry configured to receive the first set of frequency-domain diversity weights and to generate a first set of time-domain diversity weights and second IFFT circuitry configured to receive the second set of frequency-domain diversity weights and to generate a second set of time-domain diversity weights. 
     
     
       15. The diversity receiver system of  claim 14 , wherein the time-domain diversity combining circuitry further comprises:
 a first filter configured to apply a first filter response to the first channelized I/Q signal based upon the first set of time-domain diversity weights; 
 a second filter configured to apply a second filter response to the second channelized I/Q signal based upon the second set of time-domain diversity weights; and 
 combiner circuitry configured to combined the filtered first and second channelized I/Q signals from the first and second filters to generate the combined time-domain diversity I/Q signal. 
 
     
     
       16. The diversity receiver system of  claim 14 , wherein the first and second IFFT circuitry are each configured to generate a number (Y) of time-domain diversity weights that is less than a number (N) of points used by the first and second FFT circuitry to generate the frequency-domain signals having multiple frequency components. 
     
     
       17. The diversity receiver system of  claim 1 , wherein the weight processing circuitry is configured to generate a set of frequency-domain diversity weights, and wherein the IFFT circuitry is configured to receive the set of frequency-domain diversity weights and to generate a set of time-domain diversity weights. 
     
     
       18. The diversity receiver system of  claim 17 , wherein the time-domain diversity combining circuitry further comprises:
 a filter configured to apply a filter response to the second channelized I/Q signal based upon the set of time-domain diversity weights; 
 delay circuitry coupled to the first channelized I/Q signal; and 
 combiner circuitry configured to combined the filtered second channelized I/Q signal from the filter with the first channelized I/Q signal to generate the combined time-domain diversity I/Q signal. 
 
     
     
       19. The diversity receiver system of  claim 17 , wherein the IFFT circuitry is configured to generate a number (Y) of time-domain diversity weights that is less than a number (N) of points used by the first and second FFT circuitry to generate the frequency-domain signals having multiple frequency components. 
     
     
       20. A method for operating a diversity receiver system, comprising:
 generating a first time-domain channelized quadrature (I/Q) signal from a radio frequency (RF) signal received from a first antenna; 
 generating a second time-domain channelized quadrature (I/Q) signal from a radio frequency (RF) signal received from a first antenna; 
 converting the first and second time-domain channelized I/Q signals to frequency-domain signals; 
 determining frequency-domain diversity weights for the first and second I/Q signals; 
 converting the frequency-domain diversity weights into at least one set of time-domain diversity weights; and 
 applying the time-domain diversity weights to generate a combined time-domain diversity I/Q signal based upon the first and second time-domain channelized I/O signals; and 
 further comprising utilizing FFT (Fast Fourier Transform) circuitry to convert the first and second time-domain channelized I/Q signals to frequency-domain signals, and utilizing IFFT (Inverse Fast Fourier Transform) circuitry to convert the frequency-domain diversity weights to the at least one set of time-domain diversity weights. 
 
     
     
       21. The method of  claim 20 , wherein the received RF signals comprise OFDM (orthogonal frequency division multiplex) audio broadcast signals. 
     
     
       22. The method of  claim 20 , wherein a number (Y) of time-domain diversity weights output by the IFFT circuitry is less than a number (N) of points used by the FFT circuitry to generate the frequency-domain signals. 
     
     
       23. The method of  claim 20 , further comprising generating a first set and a second set of frequency-domain diversity weights with the FFT circuitry, generating a first set and a second set of time-domain diversity weights with the IFFT circuitry, filtering the first channelized I/Q signal by applying the first set of time-domain diversity weights to a first filter, filtering the second channelized I/Q signal by applying the second set of time-domain diversity weights to a second filter, and combining output signals from the first and second filters to generate the combined time-domain diversity I/Q signal. 
     
     
       24. The method of  claim 20 , further comprising generating a set of frequency-domain diversity weights with the FFT circuitry, generating a set of time-domain diversity weights with the IFFT circuitry, filtering the second channelized I/Q signal by applying the set of time-domain diversity weights to a filter, delaying the first channelized I/Q signal to generate a delayed version of the first channelized I/Q signal, and combining an output signal from the filter and the delayed version of the first channelized I/Q signal to generate the combined time-domain diversity I/Q signal.